The present invention relates to a bicycle brake lever mechanism, and more particularly to a brake lever mechanism with adjusting means for changing the return or at rest position of a brake lever relative to a lever mounting bracket or bicycle handlebar, and the lever ratio of the brake lever relative to a brake cable.
The current bicycle market is such that for any one bicycle model, there may be dozens of different types of people who may purchase that model bicycle. For instance, there may be amateur bicycle riders, professional riders, young adults, heavy set men, petite women, all interested in the same model bicycle. It is therefore desirable to provide ways to adjust a bicycle to fit almost any type of rider to minimize the likelihood of refitting specialized equipment on a standard bicycle. One such adjustment relates to the brake mechanism on a bicycle. For instance, a young teenager would not want a brake lever response that requires an excessive amount of force in order to engage the brakes on the bicycle, nor would a child want the return position of the brake lever to be five inches away from the handlebar, making in impossible to reach with small fingers. Similarly, an adult with large strong hands would not want to have a brake lever with feather like action where the brakes lock up by the mere touch of the brake lever. Nor would that same adult want the brake lever to be so close to the handlebar that his or her fingers would not fit between the lever and the handlebar.
Adjustable bicycle brake lever mechanisms are well known, such as that disclosed in, for example, Japanese Utility Model Law Application Publication SHO 62-28547. In this particular reference, a bracket is mountable to the handlebar of a bicycle. The lever bracket has a lever mounted to it via a pivot pin. The pivot pin allows the lever to pivot with respect to the lever bracket. The lever has wire locking means in the form of a u-shaped bracket pivotally mounted to a portion of the lever but spaced apart from the lever pivot pin. A brake cable is connected at its first end to the u-shaped bracket on the lever. The second end of the cable is connected to brake shoes which, when engaged, stop the rotation of the bicycle wheels in a manner known in the art.
The wire locking means is mounted to the lever by a second pivot pin, the second pin passing through an elongated opening in the lever. The elongated opening allows for adjustment of the position of the wire locking means with respect to the pivot pin of the lever and lever bracket. Since the return position of the brake lever (where the brakes are disengaged) relative to the lever bracket is determined by the contact between the lever bracket and the wire locking means, adjustment of the position of second pivot pin (and the wire locking means) relative to the lever can change the return position of the lever. In other words, the distance between a handlebar and the lever can be changed by adjusting the wire locking means.
Further, adjustment of the wire locking means allows for changes in the distance between the pivot point of the wire locking means relative to the lever and the pivot point of the lever. Changes in the distance between the two pivot points changes the amount of force necessary to engage the brakes on the bicycle. Thus the effect of the lever or the lever ratio relative to the brake wire changes depending on the adjustment of the distance between the pivot point or axis of the brake lever and the wire-connecting axis. Such an adjustment changes the operability of the brake and also changes the location of the stopping action of the lever bracket on the wire locking means which causes the changing of the return position of the brake lever.
Unfortunately, the adjustments of the wire locking means also changes the adjustment of the brake cable with respect to the brake arms and the brake arms engagement with the bicycle wheel. For instance, the brake cable may be made to tight or too loose as a result of a lever adjustment making for poor brake operability. Therefore further adjustment of the brake cable is necessary after adjustment of the lever mechanism.
The above described prior art was with reference to brake mechanisms which include a pair of brake arms which engage the wheel of a bicycle. There are also bicycle brake mechanisms in which a roller type of hub brake is mounted near the wheel axle. In such brake mechanisms, rollers are disposed between an operating member and brake shoes which are spaced apart from and housed in a brake drum. Upon application of the brakes, via pulling on a brake lever on the bicycle handlebar, an operating cam in the operating member presses and moves the rollers to the shoes, and the rollers press the brake shoes so that they contact the brake drum to create a braking force. The operating member in such roller type hubs usually have a relatively small operating stroke. In other words, very little brake wire or cable movement is necessary to engage the brakes. Hence, the adjustment of a brake cable attached to such a brake mechanism is critical.
Use of a brake lever mechanism, such as that disclosed in Japanese Publication SHO 62-28547, described above, with a hub type brake mechanism is undesirable because when the length of the brake cable is altered in any way it has a great effect on the function of a hub roller brake mechanism. Therefore, if any adjustment is made of the prior art lever mechanism, it will have negative consequences on the performance of the brake system without additional cable length adjustments.
Similar adjustment problems have occurred where the prior art lever mechanism is employed in combination with caliper type brake mechanisms where the clearance between the brake shoes and the bicycle tire rim is relatively small in order for the shoes to contact the rim promptly upon cable movement for quick effectiveness of the brake.